a Ground Test Vehicle (GTV) airframe. Early tests included fuel system calibration and attaching test sensors across the airframe to record temperature, aerodynamic load, pressure, and vibration. Two additional static GTVs underwent structural testing at the firm's Stratford manufacturing plant. In January 2013, the program had an estimated cost of US$23.17 billion after procurement of the planned 200 CH-53Ks. In April 2013, the U.S. Navy program manager stated that work had gone well and it may become operational ahead of schedule. On 31 May 2013, the Navy awarded Sikorsky a $435 million contract to deliver four prototype CH-53Ks for evaluation and mission testing; The first two prototypes focused on structural flight loads while the third and fourth validated general performance, propulsion and avionics. Major subcontractors include Aurora Flight Sciences (main rotor pylon), Exelis Aerostructures (tail rotor pylon and sponsons), GKN Aerospace (aft transition), Onboard Systems International (external cargo hook), Rockwell Collins (avionics management system), Sanmina-SCI Corporation (communications), and Spirit AeroSystems (cockpit and cabin). In October 2013, Sikorsky gave Kratos Defense & Security Solutions a $8.5 million contract for CH-53K maintenance training aids, such as the Maintenance Training Device Suite (MTDS) and Helicopter Emulation Maintenance Trainer (HEMT). The MTDS is a realistic training and evaluation environment for various avionics, electrical, and hydraulic subsystems. The HEMT is a 3D simulation of multiple scenarios, such as functional test, troubleshoot, fault isolation, removal and installation of 27 subsystems. On 24 January 2014, the CH-53K GTV ignited its engines, spinning the rotor head without rotors attached. Low-rate production is planned to proceed from 2015 to 2017. Initial operating capability (IOC) was set to occur in 2019, with full-rate production commencing between then and 2022. The USMC intends to have eight active squadrons, one training squadron, and one reserve squadron. In April 2014, testing with blades attached began, system integration followed. Flight testing was set to start in late 2014, each test aircraft flying approximately 500 hours over three years. The maiden flight was delayed, due to issues with the titanium quill shafts in the transmission and gear box. On 5 May 2014, General James F. Amos announced during the official rollout that it will be called the "King Stallion". On 27 October 2015, the CH-53K took its first flight. On 7 March 2018, one lifted a payload of , the maximum weight on the single center point cargo hook. The first CH-53K was delivered to